Generally, the configuration of a container end closure affects the level to which end consumers, as well as bottlers, manufacturers, distributors, shippers, and retailers, are satisfied with a container. One factor believed to be of some importance to consumers is the pour characteristics of the container. In general, it is believed that consumers prefer to use containers capable of providing a relatively high pour rate. Additionally, it is believed consumers prefer containers that provide a smooth or substantially laminar pour, i.e. a pour which is not characterized by a series of surges or “glugging”.
Many container configurations exist to enhance flow through a container end closure aperture. For example, some containers utilize a single large hole to admit air for venting the dispensed liquid. Examples are provided in U.S. Pat. Nos. 4,210,257; 5,007,554; 4,416,389; 4,148,410; 4,465,204; and 4,361,251; the disclosures of which are incorporated herein by reference in their entirety. Unfortunately, such larger openings tend to be associated with a higher rate of problems such as bursting, buckling, leakage, opening failures and the like, particularly when the contents are pressurized. Additionally, in configurations of large openings coupled with relatively small hinge regions, container leakage and/or separation of the panel and/or other components can be a problem upon opening. In some instances, components have been expelled from the container end closure. Furthermore, such larger openings are difficult or infeasible to provide in container ends which are relatively small.
In order to produce a more efficient, controlled flow rate, some containers utilize a tab to open two or more pour openings. This increases the flow rate of the beverage and provides better control of the liquid stream. Additionally, a second vent hole may be utilized to depressurize a container, and thus allow for easier opening of the dispensing port. This is especially advantageous for carbonated and malt beverages such as beer. Examples are provided in U.S. Pat. Nos. 4,205,760; 5,307,947; 5,397,014; 6,024,239; 6,079,583; 7,513,383; 7,748,557; 8,245,866 and U.S. Patent Application Publication Nos. 2010/0294771, 2011/0056946 and 2002/0139800; the disclosures of which are incorporated herein by reference in their entirety. However, many prior art end closures with a vent opening may be opened with finger pressure alone and utilize a score residual with a thickness which is prone to prematurely severing, and thus causing leaks or failures during stacking.
Thus, there is a need to provide a container end closure that provides enhanced pour characteristics while minimizing the likelihood of problems such as bursting, buckling, leakage, opening failures, and the like.